Nhs from 2010 experiment claim "it may work" - probably on such like those data was based those suggestion about FFP2:

https://www.hse.gov.uk/research/rrpdf/rr619.pdf

The problem is that even their narration on the begining of fake pandemics was clear:

• It has to be medical one : applying to standards (bruh,those medical ones are not enough if it would be really deadly,but ok)
• It has to be changed every time (it is not at all !) - less than 15 minutes use !
• It cannot be reused so simply (it goes to the pocket and it is weared again)
• proper fitting is ABSOLUTELY crucial

Also hands and eyes shall be protected. (gloves and some kind of glasses)

In fact proper attitude in case of real dangerous disease would be military grade gas mask with bio filter and at least gloves. OP1 demron or other hazmat suit too etc. Decontamination under showers probably with use of hydrogen peroxide.

All of correct procedure with gas mask would be procedure for bioweapon being potentially quite deadly not just bellow 1%... After wuhan not ignoring it at first months before it was clear what is really happening WERE correct way - but in fact THEN all governments were IGNORING it - what makes it if it would be really deadly point of extreme failure which would cause real disaster

But we know today it doesn't have sense as it isn't so deadly.

But are FFP2 even good ? Those research shortest summarization may look like saying yes,but its details say NO:

In principle, surgical masks that are worn correctly should provide adequate protection against large droplets, splashes and contact transmission. They may also reduce to some degree any residual aerosol risk, although this level of protection might not sufficiently reduce the likelihood of transmission via this route. Consequently they should not be used in situations where close exposure to infectious aerosols is likely (vii)

A recent published study on the performance of N95 filtering facepieces found that the workplace protection factor (WPF) for microorganisms with a mean aerodynamic diameter <5um were less than the APF of 10, concluding that even N95 respirators are inappropriate for protection against infectious bioaerosols (Lee et al., 2005). (5)

Thing being quite clear, WPF >1000 (where 1000 is 1000x reduction of exposure) would be real with military grade gas mask ONLY. And it is affordable ONLY if danger is possible to be real. Because both those masks and filters are not cheap ones. Neither useful to work using it for longer time (at least without training)

Original Lee at all research can be found here:

https://www.researchgate.net/publication/7532680_Respiratory_Protection_Provided_by_N95_Filtering_Facepiece_Respirators_Against_Airborne_Dust_and_Microorganisms_in_Agricultural_Farms

And those commonly used anti-fine masks (because currently mask protect you only against being fined !) would be useful maybe for trying to stop something if somebody is coughing. But if somebody is coughing those person shouldn't be in crowded place but in home right ?

Low quality masks were dangerous NONSENSE from the beginning,and using high quality ones now is just DUMB idea. Period.

That's the science.Real one.

There is of course "research" claiming such FFP2 would work,but on 3m (face mask producing chinese company XD) webpage so like all sponsored research it is NOT trustworthy about any safety at all.